Automatic telephone-exchange system.



1. w. LAT-TlG ac. L. eoonnum. AUTOMATIC TELEPHONE EXCHANGE SYSIEM.

.. APPLICATION man JAN. 1a. was.

' Patented July 3, 1917.

' n SHEETS-SHEET 1.

1. w; LATTIG & c. L. eoonnum. AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED um. 1a. was. I 1,232,338. Patented 11115 3, 1917.

n SHEETS-SHEET a.

J; W. LATTIG & C. L. GOODRUM.

AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

r APPLICATION FILED MN. l8. I906- 1,232,338. Patented July 3,1917,

' 1| SHEETS-SHIN 5.

W6 in wow J. W. LATTIG & C. L. GOODRUM. AUTOMATIC TELEPHONE EXCHANGESYSTEM.

umcmou FILED JAN. 18. 1906. r

Patented July 3, 1917.

ll SHEETS-SHEET 6.

l; W. LATTIG & C. L. GOODRUM.

AUTOMATIC reuzruouz EXCHANGE SYSTEM.

APPLICATION FILED JAN-13.1905. 1,232,338, Patented July 3, 1917.

ll SHEETS-SHEET I.

PatentedJuly 3, 1917.

I1 shins-sun a.

A PP LICATION FILED JAN. l8. I906.

- AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

J. W.'LATTIG 6: C L. GOODRUM. AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED JAN. 18. 1906 7 1,232,338. Patented July 3, 1917.

n SHEETS-S'HEET 9.

119i humus J. W. LA TTIG& C. L. GO ODRUM. AUTOMATICTELEPHONIE' EXCHANGESYSTEM.

APPLICATION FILED JAN- |a I905- 1,232,338. Patented July 3, 1917.

, H SHEETS-SflEET ID- shown,

J. W. LATTIG & C. L. GOODRUM. AUTOMATIC TELEPHONE EXCHANGE SYSTEM;

APH IFATION FILED JAN. 18. 906. 3,

I I SHEETS-SHEET II 'A TTORNE Yd UNITED swarms OF A'IHENS, GEORGIA,ASSIGNORS, BY'M r rnnr OFFICE.

JACOB WILLIAM LATTIG, OF ROCHESTER, NEW YORK, AND CHARLES LANE GOODR UM,

ESNE ASSIGNMENTS, TO WESTERN ELEGTRIC COMPANY, INCORPORATED, ACORPORATION OF NEW YORK.

Specification of Letters Patent.

Patented July 3, 1917 ApplicationhledJanuary'iS,1908. Serie1No.2B6,885..

'1 '0 all whom itgmay concern Be it known [that we, ilaooc WILLIAM LAT-change systems, and. particularly what are known as automatic telephoneexchange systems, and has for its object the m'iprorement thereof in themanner and-in regard to the features hereinafter set forth.

. Herctofore, most anton'iatic systems with which we are acquainted haveprovided what is commonly called a. first selector switch for each line.In some systems this first selector switch performed the function ofactually selecting the tlumsends digit of the whole ll'Ull'llJOl' of thesubscriber wanted,

and finding an idle trunk correspondingthereto; in other systems,including some oi? our own (lesi n, the first selector has beensimplified an used merely for the purpose of selecting an idle trunk toanother selector switch tln'ougliwhich the desired operation might beperformed. The second of these methods has proved to be the better inpractice,.the line switch then ceasing to be a trucfirst selector, andbecoming what is ca lied an A switch, through which the line. calling isput upon a first selector. This, however. is only one step towardsimplification; and in the present case we shall sct hirth the secondste by which the lines are not pro vided wit-1 any switcl'res, but mercywith terminals in what we shall call finders, there being number oflinescalling at once. cent. of the :u-unhe-r =o:l"l-i nes is probablysuflicient, .andin many cases a lower percentage of finders willsnlliee.

Inconjunction with our finds-1" switches we use what we s'l-mll' termstarters. the function oi which is to segregate each finder switch as itbecomes busy, by nick-lug up a calling line,.a ,nd simultaneous y torender alctive'the nextfinder switch in order, thus only so many ofthesefinders as are actually reqmr-edRtotake care ot the Ten perdistributing traflic over a plurality M155 swi'tches.- By this means thefirst incomingcall is picked up. by. the firstidle finder. switch; thesecond incoming call is taken'up, by the next idle finder switch, and so,on,; without interference. Each tinder switch constitutes the answeringterminal for a trunk line leading to a first selector or A switch, andthence the connections'and cir-' cuits being the same as in our former eetems, to which more detailed reference will be made hereinafter. Thepresent invention does not reside in the system of switches or circuitsemployed from the first selector on ward, but resides particularly inthe-arrangement and circuit connections of the starter and tinderswitches.- By our present invention each line is puivided with a relaywhich is operated when t the line calling becomes energized and renclers active the controlling circuit of the first idle finder switch,passing thereto through i. certain contacts controlled by 'the starterswitch. The. finder switch responds' by star-ti mg the starter switch,and nt-t-hc. sametime the starting circuit is altered so that so. thestarting impulse reduced to lll'fllnfilitarry duration only. The starterswitchmores one step, cuts off the finder then in operation from the.starting circuit, and puts the next idle finder thereon. The selected 85tinder switch, in the meantime, inorcsaro uld until it finds theterminals of thc'linc cal l in'g, whereupon it stops and crmnects thatline to a trunk passing to the first selector switch. At the close ofthe conversation, the subscriber in ha-i'iging up rcstor the finderswitch, as well as all the sch-actor switches, by the some operation.

Referring ,to the (hr-airings, Figure l isaf. top plan. view oi a B orfirst selectm' 'switrlh' 1 Figs. 2', 3, -31.- and 5 are details thereof;l-i' is a :top' plan view of the (i or Conner. switch and Fig. 7' is adetail rib-u" of 1 banks; Figs. 8, .9, 1 0, 11 and l zure'continuing diara-ins showing respcelnechr the .ciriOO .cfi i-tslo' the starter switchA l'hn-lcr or A I switch, first selector or it swit-h, second selectoror C switch,connector or G switcl and the lineapparatus; Figs. 8" kind8*" :1, associated diagra'rnmatiq' views naanagt; plurality :of thefinder switches 'i llustrat In these ligu'res three separate instrumentcircuits are 'shown served by four finder switches on each of whichblank contacts are shown illustrating terminals of other circuits of.w11ich there would be upward of fifty, representing an equal number oflines greater than the num'-' ber of switches. View showing a separatestarter switch and illustratin its operation in'connection with a group0 finder switches. Referring to Fig. 1, E is a base plate of metal,rectangular in shape and divided along the line 0 of its upper end,leaving an upper rim e to form a ase for the contact banks F. Upon thisbase a row of socket contacts H are mounted in insulation, with whichcooperate the contact terminals h mounted in a strip on the base E.These terminals 72. are used to complete the circuits from the cable inthe racks to the magnets shown on the base E.

The contact banks F are formed as an arc of a circle subtended by anangle somewhat less than 180 degrees, and concentric with the center oraxis 6 of the switch spindle. In the banks are the broad contacts 48,and the individual trunk contacts m, which will be pointed out hereafterin referring to the diagrams.

' Extending across the upper end of the plate E is a bridge 6*drilled'at its middle point to receive the coned end of the switchspindle 7). 'Directly in line with the o ening in the bridge a similaropening is V ormed serves to return the spindle to initial in the platefor the other end of the spindle. In a box secured around the foot endof this spindle is the coiled spring b9, which os1 tion when released,'as hereinafter described. Upon the spindle are mounted the ratchetwheels 6 and I), the stop ratchet 'wheel '6, and" the wipers b b bThese, and articularly the wipers, areinsula'ted. wiper hasan arc b,extending around the spindle, and upon these arcs, which serve ascollector rings or segments, rest the ends of contact springs I),carried in insulation on the right hand side of the bridge efl'as shownin Fig. 1, each springdiaving a'tail b for tie attachment of its circuitwire, an extension I) which receives the wiper when turned all thewayaround to clear it from the bank contacts and hold it in proper positionfor reengagement therefrom the switch.

with,this clearing being necessary when-the pla'te E and itsattached'partsare removed;

To facilitate the removal and replacing of theplate in proper alinementwith the bases of the "banks, we provide apairpfguide tongues e,.attached to the plate 0. and overlying the plate E when in position.The bank as a whole is carried on four, posts pbest' shown in Figs; 3and- 5, and each; bank of contacts is built up of insulating segmentswith the-contacts ra- Fig. 13 is'a diagrammatic.

body plate E.

dially interposed between them, the whole beingheld together by upperand lower segmental metal plates 1 secured by .throughbolts or screws fCooperating with the ratchet teeth I) on the wheel 6* is the pawl 6 on adog 6 ivoted in a yoke attached to the base-plate as shown inFigsLl, 2and :3. The dog has a joint in the middle, and a spring nor many-tendingto throw it up with the ratchet engaging, the teeth I). Cooperating withthis ratchet to form an escapement is the armature lever I) of themagnet lVlflthis lever havingachisel edge to enter the teeth, and abar bto withdraw-the ratchet as the edge enters, by forcing up the tail Z) ofthe %pposite the ratchet the dog has a toe b" with which cooperates ahook on the end ofthe spring I) carried on the end of the armature lever.of the release magnet 'M When this armature is attracted, the ratchet 6being up, the spring reaches up, the hook takes hold of the toeand-pulls down the dog, ermitting the spring Z) to return the sp1n 1e 6and all its arms to zero position as shown in Fig. 1. x I

In order to step the-wheel Z around, the

pivoted at b and having an angle sto 1).

. armature of the magnet M carries apawl b coming a ainst a fixed stop 5on the bridge *6 when t e magnet is deener ized as shown in Fig. 1. Asthe magnet T is energized,- its vertical lever is thrown tothe left, apro ]ect1on on the lower part thereof comes against the spring I) toremove it from the toe 5" and permit theretaining pawl to rise intoengagement with the teeth b", the stop I) at the. same time leaves thefixed stop 6"", the spring 6 swings the pawlb around the 'ivot 12 untilits point engages the teeth on t e ratchet wheel b each tooth on thiswheel moving the arms around over five contacts m at a jump, while eachtooth 1) moves the arnis over one contact singly. As the awl b" pushesthe wheel b around the toe 51 on the upper end of the armature levercomes over inthe path of and serves as a stop for the teeth on a secondwheel 6 furnishing a positive stop-for each step in the rotation. Eacharm hasan annular collector ring, I), as stated, upon which rests thespring bF". When it is desiredtd remove the switch body from the rack,the .arms are turned allthe way around until they rest on the fixedcontacts .Further description of "they-B and C swltches isunnecess'aryjn view of the statement of'operation hereafter, and thefullness of the illustration. It is to be underb, and comeaway-with the'stoodthat we intend to claim everything we I have shown as ourinvention.

Referring now to Figsf'fi and we will cessity for a double point outbriefly the distinctive features of the Gr switch shown herein. The onlydifference between this switch and the B and (l switches, in essentials,is in the number of relays they carry. Each of them has the same kind ofa base-plate E as that already described. Each has a similarbridge e?and each has its own spindle and arms. This switch G- has ten contactsif ten per cent. of connective apparatus is required, and twelve iftwelve per cent. There is no nem ovemcnt; there is only magnet, M and area single actuating;

lease magnet M w The arrangement of the switch base It and the framecarrying the bank contacts,

well as the sliding contact spring connections between the two, is the.same as in the The relays employed are, with one exception, of the formshown in Fig. 4. The exceptio'n i. shown in the relay M illustrated.

at the'bottolm of Fig.2, and in the middle of the bottom of Fig. 1.'illhis is a polar relay, havi iv a straight 'annature s resting on aknife go on the end of its core and tilting o e way or the otheraccording to the di n of current and consequent magnectic ,ari ty oi theiron core and armature. Straddl g the entire winding 15 a magnet Ssecured its neutral point 'to the inactive end or the core. this magnet"secured aflealt spring 3 having; its endbent up and resting upon. the'aised middle portion of the armature over fe e'dge,so asto hold thearmature in on. Alongftheother arm of the mag- *e sccurea contactspring- 18 forming one Sande release inagnet M of the connector switch,

in addition to being working magnets, each controls contacts incircuits,the functions of which will, be further. described. In eachcasethe contacts aresecured to'the frame of the magnet and are actuatedby a lever, one endof which forms the armature of its respective magnet.i

[Referring now to the circuits, first of all it will be observed that wehave shown at the subscriber-s station what are known as standardStrowger circuits and apparatus. This substation circuit needs nodescription for those skilled in thepart, but it should be understoodthat wecan substituteother suitable mcansfor operating it. The simplestform of apparatus we can use at the substation comprises twopush-buttons each connor-ting one side of the line to ground whendepressed, and an ordinary common battery talkingcircuit. To work thesystem herein illustrated the successive sets or groups of impulses aresent by grounding one side of one arm of of the circuit to becontrolled, the armature forming the other.

the line in succession the desired number of times, and grounding thenmteside of line the calling line and connects it to a B switch withwhich it is associated, The B switch steps around its arms in obedienceto impulses, each stop taking five contacts, and each five contactsrepresenting live trunks to the next order of switches. When the desiredgroupjs reached, the single impulse over the other side shifts theenergizing circuit, and the escapement magnet comes into play, steppingthe arms back one contact at a time until an idle trunk of the groupisreached. It should be observed that'theroturn movement is produced by"the ordinary retracting spring.

Having extended by those successive steps the calling snbscribe-rs linethrough to the connector G, shown in Figs. 11, 6 and 7, the connector ispermitted "to select the called line with which connection is desired,by

actuating the connector the required numberof times by impulses from thecalling partys station. 1 1

The battery connections throughout the circuits are from ground to bothsides of the line normally, and not until the called suhscriber answersis talking current cutback to the call ng subscriber. By this means weare enabled to regulate the operation of rogistering devices byemploying the polarized relay M ,'(F1g. 8) arranged in a circuitterminating in the contacts m with which the wiper a of switch Acooperates.

The balance of the circuits will be better understood from a statementof operation, tracing one call in its progress tl'irough all theswitches. as follows:

In tracing a call through from telephone A (Fig. 8) to telephone B (Fig.12), the

first operation is that of subscriber A rcmov ing his telephone from itshook, thereby closmg contact sprlngs o and 0", which are connected tothe ma n line wires by the following route: wire 3, sprlng 0, spring 0?,

wire 5, transmitter T, winding I of the in- The operation of the systemis duction coil,,'wire 1 (one) to line-"12,thus

closing the line circuit. This circuit may be traced by the followingpath: 11, 159, relay M, 158,spring 178, spring 179, wires 152, 153, tothe grounded side of battery l through batteryto wire 155, relay M wire150, spring 176, spring 177, wire 157, through mate line 12 towirc 1,completing the circuit through the A subscribcrstclca call.

* curring relay phone, as above described. This action energizes relaysM and M. In closing, the relay M operates its armature, springs 173 and174 and closing springs 174 and 175. Spring 175 is connected to groundthrough wires 161 and 153, and when in contact with the spring 174throws ground on wire 154. The object of this is to prevent any othersubscriber from calling in to this subscriber,while he is in the act ofmaking This relay M in operating also breaks the springs 170 and 171,and closes springs 17] and 172. Contact spring 171 is connected to thegrounded side of battery through wires 152 and 153, thus connectinggrounded battery to wire 160, contact springs 180 and 181,wirc 9. WVhilethis action is 00- M is also energized, but belng so constructed that itoperates more slowly than relay M itdoes not open the circuit betweensprings 180 and 181, which we have just described as completing acircuit from ground to wire 9 until the circuit of relay M, Fig. 9, hasbeen closed by the following path: wire 9, contact spring a, contact mwires 24 and 15, through relay M to wire 16 to battery. When relay Moperates, by reason of the momentary grounding of its circuit over thewire 9, it closes springs 183 and 184, also Springs 189 and 190. Spring183 is connected to ground through wire 25, contact spring a and wire195. Thus it will be seen that ground will be thrown on spring 184 and.on spring 189, through wires 21 and 25. This ground on spring 184 can betraced through wires 25 and 15, through relay LI and wire 16, thuskeeping it energized. The ground on spring 190, above described, willenergize magnet M through wire 18, contact springs 191 and 192, wire 17,through magnet M wire 14, battery, giving to the motor magnet theinitial impulse to advance the finder switch one step, additional stepsbeing imparted by which wiper a engages 'a grounded contact in the bankm and until said wiper engages the terminal'of a calling line from-whichthe ground has been removed.

M is a motor magnet of a switching mechanism similar to our otherswitches. This switch will hereinafter be referred to'as the finderswitch. When, therefore, M is energized, it revolves shaft A through theinstrumcntality of pawls anddogs, not shown in .this diagram. Shaftwipers over contact points until wiper a ceases to find a contact thatis grounded. As soon as wiper 0 passes from contact a to the groundedcontact segment a", and actuates the starter by throwmg ground throughWires 13 and 19, contact a, 'Wire 7, through magnet M flwire 8, contactsprings 193 and 194, wire 8 to battery. magnet of another switch, whichwill hereinafter be called a starter switch, WhichLreopening I A carriesa series of M is the motor POSIl'lOIl on contacts on rolves its shaft Asimilar to the other just mentioned. This mores wipers a and aover-contact banks m and m ,'respectively. These contacts are connectedto other finder switches in the same manner as contacts m and m areconnected to the finder switch, as illustrated particularly in Figs..8'and 8 and 9. Now, referring to Fig. 8, it has been above explained thatwhen relayM has been energized the contact between springs 170 and 171is broken, thus taking the ground connection from spring 170. Thisspring 170 is connected by Wire 151 to contacts m. These contacts arethe multiple bank contacts in front of four separate finder switches. Agreater or less number of finder switches may be used as described.Therefore, if any finder switch has been started, it will immediatelystop on one of these contacts. In this case, the finder switch, Fig. 9,will stop with its wipers on one of the multiple contacts m appearing inthe bank ofcontacts in front of this finder switch for this particularsubscribers line.

NV. ha re already shown how the starter 'switchstartcd the finder switchin this instance. It will now be plain that this same starter switch canstart other finder switches, shown in Fig. 8, such finder switches beingconnected to contacts m and 122?. Should there be sufficient calls fromother subscribers to step this starter switch to the last set ofcontacts-it will be released as follows: the interrupter X is soarranged that it will throw ground impulses on contact m thus it can beseen that when wiper (0 reaches contact m3", grounded battery will flowthrough contact 722-,-wi ')er a wire 6, release magnet M wire 8, tobattery, thus energizing release magnet 1W allowing the wipers on shaftA to return to their 1101111211 and m. i

We have now shown that the fin dc: switch, Fig. 9, has been caused tooperate and has placed its wipers (a, a, on contacts-m m, thusconnecting lines 29 and 30 respectively to lines 11 and 12 leading back.to the calling subscriber. I i

\Yhen the finder switch,- (Fig. 9) stopson the contacts above described,relay M (Fig. 8) will be energized as follows: spring grounded batterycurrent m wire 200, thr'ough relay L1 wiye 155 to,

battery. \Vhcnthis relay is energized the contact between springs 176158, relay h wire 159;:1150 breaking the and 177 and b'e- V tween 1-78afid'179 is broken, thus breaking the ground connection from spring 178,wire connection to relay ,M s, through 'wire 150,

springs 176, 177, w these breaks is to freethe line wlre 11 and mate 12from allc'onnect'ions with the appawire The object of' thus energizingma ratusshown in Fig. 8, and also to deenergizrelays M and M.

This completes the necessary switching operation to connect the talkingcircuit from subscriber A to the B switch or first selector.

This also closes the busy trunk by the engagement oil? the wiper c withcontact a net M over the following circuit: groun contact or, wiper a,wires l3.and 19, contacts 188 and 187, wires 1 and 34, wiper 6, wire 41,magnet M,

34 and engages a contact segment wires 40, 54, 52 and 51, battery andground.

Now, by grounding wire 3 atthe sub scribers station the jrequired"number of times to select the desired trunk leading from thefirst selector to the second selector or to the connector switch in theevent a second selector is not employed will cause magnet M to beoperated. This circuit may be traced as follows: starting fromsubscribers station, ground, wire 3,'wire 11, a wire 29,

spring 71, contact '72, wire 73, winding of magnet M wire 51, battery,ground. M in operating closes the following local circuit: ground; mainbattery, wires o1, 52, magnet Ml, :Wlle 53, spring 59, sprin- 60, wire61, spring 62, contact spring 63, wlre 65, ground. Magnet M3 by ratchetarrangement, turns shuftb, to which wipers 71 ,12 and b are at tached,causing the same to turn with shaft 6. Magnet M in turning shaft stepsit over live contacts m (Fig. 10). Now by the movement of the spindle b,the rotation of which has been previously started, the wiper I) movesinto engagement with contacts m. At the same time wiper I) cuts out thewire connected l8, against which it restsafter *tothe wire of its normalposition, allowing inc-ring out the magnet M to be energized bycurrent nholding circuit: ground, mam

the followin a 52, 54, and 40, magnet- M,

battery, wires 51, wire, 41, wiper bi, wire at magnet M wire 44,contacts 77 and78, wire 7 9 to ground. i Therefore, M would continue tohold up even. thougl'i the spindle b was being turned by, magnet M Wewill now close the'circuit from ground once at subscribers station overwire 1, (one) wire 12, contacts we, wiper a, wire 30, contacts 74 and'75, wire 76,;winding on MLwire 50, battery to ground; this, operationof the magnet M would. open contact. between springs 77 and 118,depriving M- of itsssource of ground,

which would then, if the wiper if? of the i switch was at that timestanding on a ground on busy contact of ml, continue to hold up M: .ifthen the wiper 7); does not happen m-have' a source of ground, M wouldthere for) have to release or drop back, extending Huglincs that it hadjust previously opened to the first selectons'witch (Fig, 10) andcutting oil' the magnets M and M that it ture no longer.

48, contacts 47 and exists until the relay had just previouslyconnected. If, however, the wiper I) was on a grounded contact, thenwinding of M would hold up over this ground as well as M. We wouldalsothen have a circuit through M starting at m, supposing it wasgrounded, 6 wire 43, winding of M wire 44, spring 77, contact spring 80,wire 81, wire 82, Winding of M, wire 50, battery,.ground. We thenghave acircuit through magnet M in parallel with the circuit of M, from wirecontact spring 85, wire 86, winding of M" wire 87, wire 50, mainbattery, ground, Magnet nectexl with shaft 6 and. when ener ed makesand. breaks its own circuit 1i e a buzzer. Shaft 6 being under tensionof a retractile spring drops back one contact with each step. S0 in.this manner we travel backward over contacts m so long as b can findground- So as soon 'as W er b loses ground we then notice that M, losetheir circuit, consequently releasing, and in consequence M also isdiwonnectc d from battery and will, therefore, vibrate itsarmal.herefore, all the relays of B switch are'normal. A circuit may nowbe traced from contact m back through 12, wire 43, M wire 44, spring 77,spring 78, wire 79, ground. Since wiper b, on m is grounded and currentflows over a circuit from contact m wire 49, (Fig. 10) wire 88, 0 wire89, M, wire 90, main battery,

- ground, relay M is thereby caused to oper-.

ate, causing it to open its normally closed contacts and close itsnormally open contacts, opening wire 91 from 94, and wire 92 from wire93, and cutting wire 91 onto relay M and wire92 onto relay M f. Now,therefore, when Wire 3 (Fig. 8) at sub.- scribers station is groundedone or more times to select the trunk leading to the second selectorswitch,,it will be seen that re lay M operated, which. acts to. energizeM. with each impulse of current causing it to turn the spindle .lo asuflicient distance to move its wipers througha space of five contacts.

When the shaft 0 takes its first step, the

brush 0 passes from the terminal of wire 88 on to the terminal of wire480, thus inter-- winding M is similar in action to'M' and is capableunder proper condition ofbeing actuated by successive impulses ofcurrent from the calling subscribers station Whenever the line 3.1sgrounded, which condition W-i g ounding wire 1'(one)' at subscribers 81,spring 84:,

a substitute circontacts of relay M is deenergized. 9

station once causes M to be operated b current in the following circuit:

the windingof M in parallel, contacts m,

, Fig.- 10) ground m.

m ,,.wire HQ-winding of relay MP wire 430 and wiper 0 to terminalcontact m As the original energizing winding for M passes throughnormally open contacts of relay M it will be seen that the continuedenergization of M, M and M is dependent upon the contact m on whichbrush c rests, being grounded. If the trunk represented by this conta tis idle, no ground will he on contact an and the above relays willbecome deenergized and no further movement of the switch shaft 0 willtake place. If, however. a multiple of the contact m is engaged byanother. selector, m will be connected to the wiper c'- winding ofground through said multiple, of the switch thereon, wire 130, M andcontacts Wt ,.7)t to ground, thus relays M and M will be liiaintaine'denergized and the magnet M, which interrupts its'own circult by everyenergization at contacts m, will be intermittently energized to permitthe shaft 0 to rotate backward step by step until wiper 0 fails to findground on the terminal contact m of an idle. trunk, when the circuit forrelays M, M and the. magnet M will be interrupted. as before described.The dei nergization of relay M by closing conm m places ground on thecontact m; thus making the trunk busy. Thiscil cuit may be traced overthe following path: contact m, wire 440.

i'nagnet iii, wire 430, wiper 0", contact on. (Fig. 11) wire 95, wiper 7wire 96, M, wire 07, battery to ground.

We, therefore, see that M'. will be energreed. opening its normallyclosed contacts and'closing its normally open contacts. causing wire 08to be separated from wire 5)!) by contacts [00 and causing wire 100 tobe sepa araled from wire 10] by contacts .100. We also seethatconnectedto wire 08 we have, magnet M wire 102, spring 103, spring 104, wire 105to main battery and ground; On wire 100 we ha \e tapped niagnct- M,wirelllli, spring 107. contact. spring 108, wire 100, spring 1 l0.contact spring 1 l 1,, wire 112, wire lllfi'to main battery ow supposethat. we'groiii'iil wire '3 at s 'l lisc 'r 'l'i "s stationthe necessaryimunbcr of o operatethe selected connector switch to iiiiu se its wipers.divid-ual line),

to take up the terminals of the called partys line. Each time wire 3 isgrounded, a. 011'- cuit is completed from ground at substation .over theupper talking strand of the line now complete through to wire 98, Fig.11, 70 winding of magnet M contacts 103 and 104. to battery and ground.Each energizetion of M completes a circuit'from battery, through wire98, contacts of M "now energized, the winding of M, contacts of M andcontacts of M to battery, tlius energiz ing M. Magnet M moves the shaftand its wipers forward one step or one set of contact terminals eachtime it is energized. was originally It was just described how Menergized through wiper g. This original circuit through is brokenwith.the first step of the shaft 9 butanother circuit for relay M is nowestablished, from battery, over wire 97. winding of M contacts of 11"and contacts of M back to battery. 'l'here't'ore as long as M remainsnormal, M will be held up and the shaft. can be stepped around as far asdesired. Now grounding the lower talking strand of the line atsubstation A completes a circuit over. the lower talking-strain'l of theline, through relay contacts 107, 108. contacts 110 and ill to batteryand ground. This will operate M'-'j-, interrupting the circuit justtraced for the relay M. if (he called line is idle, M will become dtanergized, extending the talking strands 9b and through to the brushes ofthe switch 9. All of the relays will now he in their normal condition.'Now. 100 We will suppose that the cont-act m on' which lh'e. shaftplacedthe wiper g was busy. (heinggrounded tooperate M to clear the lineduring the lime connection is estab lished therewith) we would then have ground on this contactso, therefore, considering ground on thecontact m wiper 5], wire .l-Zl. wire 117. spring 116, contact spring]15. wire. ll-l. wire 113. 1V .wire 97. battery t ground. 'lhcrct'orc. ifthis line is busy, magnet M will remain held up and will not relcaseeven though Mf-iis operated. which will prevent any one {from coming inon a line that is has Now. again, supposing that the line was not busyand the connector switch did cut through. we will notice that'when M'"and M drop back. we have ground (.l ig. 11) by wire 120. spring 115contact spring 118, wire 117. wire 121 to' g oi rtoa contact m" (Fig12.) wires 122,123,.M, wire. 124 to main battery and ground, whichcauses M to operate. Wires 125 and 126', (supposed to bB'tll(5(',tlll((l subscribers inare thus cleared from an connection with A".representing the multi 125 ple-eouta-cts of said line in front of thetinder switches. Now,*we therefore havegonethrough .and'connected withthe de-' sired line (it. is understood that wires 1'25. and 126 extendtosubscriberstation). .W'e 130 circuit o'l M. and M? is as follows:ground.

now know with M in its normal condition and shaft 9 oil normal, that 51engages the interrupter which makes and breaks the ground, and thereby-M is caused to be drawn and. held for an instant then released, thenagain drawn up and released, etc, as long as the conditions justdescribed are true, over the following circuit: ground, interrupter 300wiper y, relay magnet M springs 301., 302, 302- and 30%, wire 30;), tomain battery. 'l hus M operated in this manner, as shown. by thecontacts, throws a ringing current out to the called subscriber, ringinghis telephone il'itermittently until he answers or until. the callingparty hangs up. N on, supposing that the called party answers. itwill'hc noticed that M is tapped on to one side of the line, the otherside of the winding going through wire 10?) to main hatter It will alsobeuiticed that h is tapped on to the other side of the line and theother side to groind. So, therefore, thecalled party in taking hisreceiver oil the hook causes NP" and M to act. closing their normallyopen contacts and opening their normal l v closed contacts. It will henoticed that M and M have their circuits open when M? acts. It will alsohe noticed that M" and .\l'-'" have their circuits normally open. hutare closed as soon as M acts. The

wire 1120; niagrncl M. closed contact springs on magnet M to the side ofthe line represented in JH back through the. several switches tosuhscrihens station, thence by the othcr'sidc oi the line to wire lOO,contacts on relay M, to relay N1 and mai lialh-ry. 'lhcrelore. thecalled party in tali-i mg his-receiver oll' has done two things: cuttingoll' M and M and cutting on M and'bP". and in this way has given, thecall.- in; par! v what we might term talking cur rent." Now after theconversation is fillishcd. ii the called party hangs up first hei'nllscs holh sides or his line to be grounded.

. and then the line side, 1525, to be opened.

while the mate side, 126, is still grminded. To accomplish i'lns thcsuhscrihers sub-stalion is so construcltal lhat'itwill hold ground aninstant longer on the hattery side of the lino than it does on thegl'UlHH'lBd side of the line and which operates the release over thefollowing circuit: ground, main batterywires PM; and 316. s n-inns 317and 31.8, wire Wires 323, 314 and /a' and wil and ground. By thisoperation. it will he soon that M drops hack and that M holds up,('losinglhe release circuitiot M ovi-r the following path: (Fig. 11) hattery. contact springs on WP (nowweloscd). contact sprinyzson NP (nowclosed) magnet M. hank contact wfifflig. 10) wiper .0 wire $30, magnet1V wire MO, springs n i), ground.

M and the latter operating causes its local magnet M to act by anin'ipu'lse ofcurrent traversing the following path: (Fig. 10) battery.magnet M, contacts on M, wire l9, hankcontact m (Fig. 9) Wiper b Wire+3, relay M", wire i l, springs 77, 78', wire This circuit causes M toact and close its local contact and energizethe circuit of M and'M,traced as follows: ground, wire 79, springs 38, 37, wire 33, magnet Mwire 14- ,to battery also from wire 33', to wire n'iagnet M, Wire .34,52, 51 to bat tery. Therefore, when M loses its ground the entire set ofswitches is released to return to normal. it thefealling party hangs upbefore the called party, then the calling party momentarily grounds bothsides of the line, then ln'eaks the line side, 98, which includes M. andthe mate holding up M over the following circuit: gronl'id main batteryB. wires 306 and 307, springs 308 and toll. wire SH). springs 311. a d.312, wires sides of the line would he closed inomentarily when thecalling party hangs up, causing ME" and hl to pull up at the saline timewhich closes-the release over the follow- I inn circuit: grouiid. mainbattery, wires 306 and 524-, sprinn's i-llfi, 326 and 327, wire 317:.ina nut .\l'-. wire 95. contact M wi ier r5 win no. magnet on, wire 440,springs pm' and 1/8"" to ground and thereby releases the switches.

Having. thusdescribed our invention, we claim: 1

1. 11:1 an autoniatie telephone system, the ronihimition with aplurality of normally open instrunuut wircuiis having terminal contactsarranged in ii switch hank, norl'nally I closed operating circuitbranches and normally open stariing circuit l 'anchcs corresponding toeach instrument circuit; terminals for thc operating; circuit branchesarranged in 1-1 switch hank and Wiperscoiiperati'inr'with said hanks. ofa line relay bridged ,to each inslrlnncnl circuit and adapted to opcnits corresponding hranrh operating cir cud. wipers cooperating with thed llcrent hanks of contacts and elcclroinagncl'u' opersiting nnchanisinl'or automatically advancjinn said wipers progressively which adaplcd tohe :n-iualcd hy the closing ol a hranch starting circuit and lo continuethe movement ol'lhc wipers during the sucrrs' sire cngagrnu nt of oneo'l' them with the ter- 'n|inals ol" closed operating circuit hranrhcs.

:li'lll-oll relay also associated with each inslrinncnl circuit adaptedto openitsline relay while. the latter continue to engage the ter-.

branch operating-circuits corresponding to each instrument circuit alsohaving multiple terminals arranged in banks on the various switches andseparate wipers on each switch cooperating therewith, ofnormallyinoperative electromagnetic operating devices for each switchmechanism fol-automatically advancing its respective wipers" as one ofthem successively engages the terminals of closed operating circuitbranches, a starting mechanism for rendering said devices capable ofoperation, a. local starting circuit for sup 'ilying an initial impulseof current to starta switch mechanism which is connected to saidmechanism by the sta; Ping operating devices. normally open branches ofsaid local circuit corresponding to each instrument circuit, meansforclosing them and opening the corresponding operating circuit branch anddevices actuated upon the movement of each switch in turn to operate thestarting mechanism to connect the local starting circuit toanotherswitch. v

3. In an automatic.telephone system, the

combination with a plurality of switching mechanisms comprising banks ofterminals and wipers cooperating therewith, a plurality of instrumentcircuits connected in multiple to terminals in the several banks, ofnormally ino -ierati ve electro-magnetie operating devices for eachswitch adapted to be rendered active to advance. their wipers ininals ofopen instrument circuits, a local starting circuit having normally openbranches corn-spolnling to each instrlnncnt circuit, two relays havingdill'erlrn-t time constants bridged to each instrumcntpircuit andvcontrolling its (;Ul'l(S[')(Jll(llll, branch operatlngcn'cuit, therelay responding to current impulses with less rapidity being," ,adaptedto open said branch after the t|llll est relay [has closed it, aswitch-starter ianism arranged in the local portion. o ing circuitcomprlslng ternnnag i-icctromagnetlc operating llOVlt't'S ol cl 0 startiljor the the sevl i v1 cral switches and a wipercooperatlltgdthurelin-lzh anlsnr starter cn .with, thel'nnction ol' thestarter be ng to successively conncctthc cuit with onc or another oftheslwitdh operating mechanisms. and devices l'iir actuat iiigthcstarter mechanism.

having a circuit adapted to be closed to acless in number 4. In anautomatic telephone s Stem, the

combination with a plurality o switches comprising banks of terminalsand wipers cooperating with them, electromagnetic mechanism foradvancing said wipers embodying a motor magnet having a normally opencircuit, a controlling relay associated therewith for closing saidcircuit and a local starting and a local operating circuit over whichcurrent may be supplied to the relay at difi'erent times, of a starterswitch mechanism comprising terminals for the control ling relay of'eachswitch and having a wiper cooperating with said terminals, a pluralityof instrument circuits connectedin multiple to terminals in the variousswitch banks, branch starting circuits corresponding to eachinstruih'ciit circuits connected in multiple to terminals in the variousswitch banks, branch starting circuits corresponding to each instrumentcircuit termiliating in the wiper of the starter-switch, o ')eratingcircuit branches also corresponding to each instrument circuit andhaving multiple terminals arranged in banks on the various switches,wipers on each switch arranged in the'local operating circuit of itscontrolling relay, means associated with each instru mentcircuit forclosing its corresponding starting circuit branch and opening itsoperating circuit branch, and means fonadvancing the starter-switchafter one switch has been operated to render another switch in conditionto be operated.

5; In an automatic telephone exchange system, a plurality of subscriberslines, a line relay for each line, a plurality of finder and selectorswitches, a relay for each-tinder switch, a starting circuit for thetinder jointly controlled by the said relays to produce a momentarycurrent in the starting gircuit, and means to restore the switches onthe completion of a communication, substantially as described.

'3. Tu an automatic telephone system, a plura lity of subscribers lines,finder switches than the number of lines, and means for operating saidfinder switches to find the line when said line is closed, selectorswitches connected to said finder switches, and two magnets for saidselector switches adapted to be operated over opposite sides of theconnected line, one of said magnets being arranged to produce a longstep'over a series 01' contacts in said switch and the other magnetbeing arranged to produce a series otshort steps to terminals of thelines passed over by the long steps.

A telephone exchange system comprising aplnrality of telephone lines, apluralto its final selecting movement to free said master switch forfurther use, and means for actuating said master switch once and onceonly per call.

8. telephone exchange system includin telephone lines, a plurality oiselectors eac I having access to sa1d lines, a master switch forstarting idle selectors to establish connection with calling lines, astarting circuit normally extending from said master switch to an idleselector, and means actuated by a started selector prior to the finalselecting movement to free said master switch for further use.

9. A telephone exchange system includin telephone lines, a plurality ofselectors each having access to said lines, a master switch for startingidle selectors to establish connection with calling lines, a startingcircuit normally extending from said master switch to an idle selector,and means for adjusting said master switch and connections altered by astarted selector prior to'its final selection to free said master switchfor further use, said means then serving to adjust said master switch toestablish a starting circuit extending to another idle selector.

l0. 'ln-a switching mechanism, the combination with a plurality ofterminals, a branch circuit leading from each terminal, a, contactelement cooperating with the terminals. and a spring operated device foradvancing the element, of a motor magnet for setting the device inactuated position against the tension of the spring, a circuitcontrolling the operation of the motor magnot which is completed overone or another o't the circuit branches upon each advancement of thecontact element to effect the energ'izing of the motormagnet and meansfor I subsequently breaking said circuit to eflect the deener'gizing ofthe motor ms. t and a source of current supply for said circuits.

11. The combination with a plurdlityof lines, of a plurality of finderswitches for makin connection therewith, a starting circuit a apted tobe closed by any of said lines in calling and adapted to start one ofsaid switches, means made operative at the outset of the movement ofsaid switch for advancing said starting circuit to the next switch, andmeans for preventing said calling line from starting said next switch.

12. The combination with a plurality of lines, of a plurality of finderswitches for makin connection therewith, a starting circuit with whichone of said switches is in operative relation, means actuated by anyline in calling for closing said starting circuit to start said switch,means actuated by said switch at the beginning of its movement forbringing another finder switch into operative relation with saidstarting circuit and means for depriving said callin line of control ofsaid starting circuit be ore said second switch comes into operativerelation with said starting circuit.

In testimony whereof I ailix my signature in presence of two witnesses.V JACOB WILLIAM LATTIG.

\Vitncsses:

I'lURAllO Srnaos, Josnru ll. VEBSTER.

In testimony whereof I afiix my signature in presence of two witnesses.

CHAR-LES LANE GOODRUM.

\Vitncsses:

M. H. SKALOWSKI, Hownrn Conn ERWIN.

